Multi-scale evaluation of the energy and water balance of the ORCHIDEE model on Siberia and response to climate change.

• Main Author: Dantec-Nédélec, Sarah
• Other Authors: Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université Paris Saclay (COmUE), Catherine Ottlé
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2017
• Subjects: Climate change; Vegetation; Hydrology; Land surface model ORCHIDEE; Siberia; Changement climatique; Végétation; Hydrologie; Sibérie; Modèle de surface continentale ORCHIDEE; [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; permafrost
• Online Access: https://tel.archives-ouvertes.fr/tel-01564459; https://tel.archives-ouvertes.fr/tel-01564459/document; https://tel.archives-ouvertes.fr/tel-01564459/file/70865_DANTEC_2017_archivage.pdf

The natural evolution of the climate, disturbed since the industrial revolutions, is strongly marked in the high latitudes especially in Siberia where a temperature anomaly of +0.8°C has been observed since the 2000s against an average anomaly of + 0.4°C for The mid-latitudes. Siberia is covered by permafrost, giving it particularities, especially for the hydrological regimes of rivers. Climatic projections predicting up to +5°C warming by 2100, it is essential to evaluate their impacts. Physical-based numerical modeling is an interesting tool to answer these questions. Thus, in order to evaluate the hydrological response to climate change in Siberia we worked on the multi-scale evaluation of energy and water balances with the ORCHIDEE model. This model was adapted to the characteristics of cold environments, with an improvement of the representation of the snow, a consideration of the freezing of the soil water and a map of vegetation more representative of the Siberian vegetation. An evaluation in forced mode i.e. without coupling with the atmosphere was carried out initially. Thus, we evaluated ORCHIDEE at the present time (1979-2009) at the site scale, concentrating on the soil moisture and soil temperature data available. A sensitivity analysis of the model allowed to identify the most influential parameters on the balance of energy and water in the soil. Their on-site calibration allowed to show that the ORCHIDEE model is able to correctly simulate the vertical transfers of heat and water and the resulting water and soil temperature contents. We then extended the evaluation to the Siberian region by comparing simulation results with remote sensing data, allowing an evaluation over a substantial time series and over a large area. We collected a large number of observations such as albedo data, water equivalent for snow ., on which we compared the simulation results. This work allowed to show that the model simulates satisfactorily the energy and water balance in Siberia, but also to highlight the importance ...